Author: Frederic Massart
MDL-46191 gradereport_history: Missing filename when downloading data
http://git.moodle.org/gw?p=moodle.git;a=commit;h=a2bf889706401fec9c6fa6db0e7e8c1ffd73d826
http://github.com/moodle/moodle/commit/a2bf889706401fec9c6fa6db0e7e8c1ffd73d826
+ 2.8 en [exportfilename,gradereport_history]